Light sources such as light-emitting diodes (hereinafter, abbreviated as LEDs) and organic ELs have been widely used as illumination as well as backlights of displays, taking advantage of features of low power consumption and long life, and are likely to be increasingly used in the future. In order to efficiently utilize light from these light sources, reflective materials to reflect light from the light sources have been utilized in various situations. In addition, reflective materials are required to exhibit high reflectance under the operating environment.
In recent years, due to the requirements for cost reduction of products, it is required to decrease the number of light sources (LED packages) installed in final products such as televisions and displays. Accordingly, it is required to enhance the reflectivity of reflective materials and more efficiently utilize light from light sources.
For the material for such a reflective material, a resin composition is proposed, for example, in which a glass fiber or titanium oxide is blended in a melt-processable polyester such as an aromatic polyester and an aromatic polyester amide (e.g., PTL 1). The resin composition is satisfactory in heat resistance and dimensional stability to some degree. However, it is difficult to sufficiently enhance the reflectance of a reflective material consisting of the resin composition.
In view of this, a resin composition for a reflective material is also proposed, the resin composition containing a polyamide resin containing a structure derived from a cyclohexanedicarboxylic acid, titanium oxide, and a reinforcing material (PTL 2). The resin composition enables to obtain a reflective material having high whiteness and high resistance to reflow soldering heat.
On the other hand, for a material for optical films is also proposed a completely-alicyclic polyester containing a structural unit derived from a cyclohexanedicarboxylic acid and a structural unit derived from a cyclohexanedimethanol (PTL 3). The technique allows the proportion of the trans-form in the structural unit derived from a cyclohexanedicarboxylic acid to increase to enhance the heat resistance of a film to be obtained.